Answer:
We can use the equation for the location of the bright fringes in a double-slit experiment:
y = (mλD) / d
where y is the distance from the central maximum to the m-th bright fringe, λ is the wavelength of the light, d is the distance between the two slits, and D is the distance from the slits to the viewing screen.
We are given λ = 670 nm, d = 0.3x10^-3 m, m = 4, and y = 0.05 m (the distance from the center to the fourth bright fringe). Therefore, we can solve for D:
D = (y * d) / (m * λ) = (0.05 m * 0.3x10^-3 m) / (4 * 670x10^-9 m) ≈ 1.12 m
the distance from the slits to the viewing screen is approximately 1.12 meters.